1. Field of the Invention
The present invention relates to an information processing apparatus having a communication function and a power control method therefor.
2. Description of the Related Art
Conventionally, in an information processing apparatus, power saving is implemented by powering off most units and or functions of the information processing apparatus while no communication is being performed. In performing communication, the information processing apparatus is powered on via a network, for example. Such information processing apparatus is typically capable of performing an application communication using TCP/IP protocol as a lower layer protocol via a network.
The method of saving power in a personal computer (PC) connected to a local area network (LAN) includes the following methods. During power saving, a personal computer (PC) powers off a main device such as a central processing unit (CPU) and a hard disk. The PC then activates only a network interface controller (NIC) which is directly connected to a network for controlling communication. In addition, during power saving, the NIC checks if a data segment received from the network includes a specific data string. If a data segment including the specific data string is received, the NIC performs control to activate the main device of the PC.
The aforementioned method is generally called a “Wake-On-LAN (WOL)”. A representative example of application of the WOL to a PC includes “Magic Packet®”. Referring to FIG. 1, a data string 201 indicates the format of a specific data string in Magic Packet®. With the use of Magic Packet®, the NIC activates the main device when receiving the data string 201, which includes data 202 having a six-time repeated hexadecimal number “FF . . . ” followed by data 203 having a sixteen-time repeated media access control (MAC) address.
Referring to FIG. 2, a data string 301 indicates an example of Magic Packet® using a User Datagram Protocol/Internet Protocol (UDP/IP) packet. The data string 301 includes an IP header 302, a UDP header 303, and a data string 304, which is a specific data string in Magic Packet®, as a packet payload (data body).
Furthermore, Japanese Patent Application Laid-Open No. 2000-11316 discusses a method for powering on an application apparatus via a network to activate the application apparatus.
However, in the case of WOL, it is necessary that an apparatus that activates an information processing apparatus via a network includes a function for producing a data segment including a specific data string. Accordingly, apparatuses that are capable of remotely activating an information processing apparatus are limited. For example, in the case of Magic Packet®, an apparatus that remotely activates an information processing apparatus needs to previously store a MAC address of the information processing apparatus to be remotely activated.
In addition, an apparatus that remotely activates an information processing apparatus needs to have a function for producing a sending data segment having a data format such as the one indicated by the data string 201 in FIG. 1.
Moreover, in the case of WOL, an apparatus that activates an information processing apparatus needs to perform a communication while determining whether the information processing apparatus is in a normal operation mode (normal power consumption state) or in a low power consumption state.
Therefore, it would be desirable to provide an information processing apparatus capable of saving power consumption and safely performing restoration from a low power consumption state according to a request from another apparatus connected thereto via a network, with a simple configuration.